GRAVITY MAPPING OF KARST ALONG STATE ROUTE 269 IN BELLEVUE, OH

Sinkholes north of Bellevue, OH become springs when the water table rises, flooding homes, fields and State Route 269. We are using gravity and electrical resistivity to investigate a sinkhole complex associated with a topographic depression about 4 km² in area. A total of 123 gravity stations at a spacing of 20 and 25 m were occupied along State Route 269 covering a length of 3.1 km while another 154 stations were occupied in the adjacent roads. Two gravity lows of maximum amplitude of 0.1 mGal with a length of 1.0 km and 0.6 km and width of 0.8 km and 1 km are delineated. To determine the extent of karst development, the volume of the missing mass was calculated using Gauss’s theorem of anomalous mass and it ranges from 1.68-9.76*10⁶ m³ depending on the infill material. Based on the volume of the missing mass, a karstic porosity of 1.3-7.5% is estimated.